The invention relates to a liquid crystal filter, a color filter substrate and a manufacturing method thereof.
A Liquid crystal display (LCD) device comprises an array substrate and a color filter substrate assembled together with a liquid crystal layer interposed therebetween. The array substrate comprises gate lines, data lines, pixel electrodes and thin film transistors (TFTs) that are formed thereon. The gate lines and data lines cross each other and define pixel regions, in which the TFTs and the pixel electrodes are formed. The gate lines provide gate signals (e.g., ON signal) for the TFTs, and the data lines provide data signals for pixel electrodes in the pixel regions. Images in gray scales are displayed by controlling the twisting or deflecting of the liquid crystal in the liquid crystal material. The color filter substrate comprises black matrixes, color resin units, a protection layer and a common electrode layer that are formed thereon. The color resin units may comprise red, blue and green resin units. Black matrixes are disposed on the color filter substrate for separating color resin units and preventing light from leaking.
The black matrixes on the color filter substrate are generally formed on positions corresponding to the gate lines, the data lines and the TFTs formed on the array substrate. In this way, light incident from the color filter substrate side can be blocked by the black matrixes so that light from outside can not be incident on the channel regions of the TFTs, ensuring the electrical characteristics of the TFTs. However, it is found that light from the array substrate side (such as light from the backlight provided under the array substrate) may result in degradation of the electrical characteristics of the TFTs. Researches show that when light from the backlight is incident on the black matrixes at an inclined angle, even if the black matrixes may absorb most of the light, a part of the light is reflected by the black matrixes and incident into channel regions of TFTs, which causes the TFTs to generate a relatively large leakage current. Increase of the leakage current of the TFTs makes voltage sustaining rate decrease, which causes an abnormal black display in normal white mode such that contrast ratio is degraded.